Aircraft: WIDEBODY TRANSPORT
Phase of flight: Initial Approach
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy

Hand flying A/P and A/T off descending from 2;400m to 1;800m while being vectored to the ILS 02R final; ATC issued a runway change to 02L. My misplaced confidence in selecting the correct EFB approach plate and making the required Baro DH change while simultaneously leveling off at 1;800m was obviously the major factor. Complicating the situation was the new EFB software. It is far from intuitive and the touch screen accuracy; despite repeated calibration; is anything but accurate. Additionally; I attempted to set the new DH while the altimeter was set for meters; further distracting me from my primary task of flying the jet. I recognized my error descending through approximately 1;770m with a max deviation of 50m (approximately 150 feet) before correcting back to 1800m. ATC soon thereafter issued a descent down to 1;200m.I have several suggestions. 1. Aviate; navigate; communicate; fly the jet first always! 2. Last minute unanticipated changes by approach control on base to final; A/P and A/T on. 3. The new EFB software is a SITUATIONAL AWARENESS black-hole. Definitely a major detractor in all flight phases. 4. Company required EFB training and self study accessible training aids totally inadequate. JEPPS change is about money with apparently a total disregard of the real/potential safety implications. During descent; First Officer flying; First Officer decided to fly aircraft manually from about 10;000 feet. We were on vectors downwind descending to assigned altitude of 1;800 meters. At some point; approximately 1;000 to 2;000 feet above level; approach issued a runway change from 02R to 02L. I went heads-down and changed the approach in the FMS; then selected the new approach chart on the EFB as we approached level-off. As I was working on the EFB; I heard the 'altitude' CAWS alert; followed by the First Officer verbally state '1;800 meters.' My attention immediately shifted to the PFD; and I saw that we were below the assigned altitude; with the First Officer correcting back to the assigned altitude. With 1 to 2 seconds of this; and while the First Officer was still correcting; ATC issued a further descent clearance to 1;200 meters. My estimate is that we were never more than 200 feet below the assigned altitude; although I did not actually see the altimeter until we were already correcting back to 1;800 meters. Both other crewmembers stated that the deviation did not exceed 150 feet. Threats: Workload. When the First Officer decided to fly the aircraft manually at about 10;000 feet; the workload level was quite low. The approach had been briefed; we were on vectors; and traffic was relatively light. However; multiple communications from ATC; multiple altitude step-downs and heading assignments increased the workload somewhat. The runway change increased the workload significantly. The electronic charts are still new to us (my fourth leg using the system) and require more time and mental concentration than usual. This would have been a good time to discuss using the autopilot to reduce workload; or at least otherwise communicate that workload was becoming a factor. Gradually increasing workload needs to be recognized. Forthright communication between crew members that distractions increasing; and offering options to address them would have helped. We had already discussed that the new charts were an issue. My ability to effectively monitor was diminishing as my workload increased. Although we were honoring the sterile cockpit procedures; I could have managed necessary communication better. During our debrief; we all agreed that re-engaging the autopilot would have been a good choice as soon as the runway change was assigned. Only one person had to state 'I'm getting busy' to totally change the dynamic. Pilots tend to be reluctant to change a plan once it has been implemented. In this case the changed plan would have been to re-engage the autopilot. We acknowledged that we did not recognize the 'red flag' of distractions associated with gradually increasing workload. Situational awareness and communication associated with workload when manually flying are key to not repeating this event. A flight crew using a new EFB software package commented about distractions caused by the lack of its usability and the First Officer overshot an assigned altitude while searching for a DH after a runway change.